A carrier aggregation (CA) scheme corresponds to technology of enhancing the efficiency of data transmission by merging a plurality of component carriers. A terminal or a base station may be assigned with the plurality of component carriers and may transmit or receive data using the plurality of component carriers.
The terminal or the base station may transmit control information associated with the data. Acknowledgement/negative-acknowledgement information (ACK/NACK) and an amount of assigned radio resources may be used as an example of the control information. There is a desire for research regarding a component carrier used to transmit control information among a plurality of component carriers and the control information to be transmitted when the plurality of component carriers is assigned.